I wanted to set up a 3 volt single LED to be able to adjust the brightness from OFF to maximum brightness. I was using a pot switch, but read this is not a good idea. I would like to have the adjustment by turning a knob or pushbutton. I could not find the parts I need. Any help/advice or links to manufacturers would be greatly appreciate. I am pretty novice at this.
Thank you.

 

The simplest method aside from using a micro controller would be building a simple 555 timer circuit and adjusting the duty cycle. As long as the frequency is above a few hundred hertz it'll appear to be on continously and the larger the duty cycle the brighter it will appear.

__________________

 

Would I be able to power it off with the 555 as well? Also do you have a website link that offers the components I may need?

 

You can if the pot is designed to handle the LED current. Most carbon "Audio Pots" are not and will go intermittant after a while. To get around this, you can use the following circuit: (I didn't put any resistor values in there because you don't mention what voltage your supply is)

Attached Images

LedDimmer.gif (3.2 KB, 38 views)

__________________
--- The days of the digital watch are numbered. ---

 

Thank you this is currently how I have it set-up. Unfortunately I won't the pot to serve as a switch as well and cannot find anything small enough. Any recommendations on where to get a pot switch that can handle the LED?

 

If you use a 1M pot and a 6V battery then with the pot turned down the current in the pot is so low that a battery will last for a very long time, it shelf life. The transistor will need to be two connected as a darlington or use a darlington.

__________________
Uncle $crooge

 

You/I need to know what the max LED current and supply voltage will be first. For higher power you can use a wirewound pot, but the carbon pot / transistor method will be cheaper and easier to find parts. You can do away with the swicth on the pot if you wish, but this will means that there will be some current draw when the LED is off. Again, the carbon pot / transistor method will be better in this regard.

__________________
--- The days of the digital watch are numbered. ---

 

Power supply is 3 volts.

 

You should be able to find pots that have an off detent, a lot of consumer electronics equipment use them. What resistance that off detent provdies I'm not sure, but it's going to at least be as good as 'far left' on a regular pot, and provide a physical detent preventing accidental turn ons.

__________________

 

That will make it much more complicated. Can you go to 4.5V? The problem with using a 3V supply with a 3V LED is that there is no voltage left to drop through a resistor and thus you cannot easily limit the max LED current. You will need to go to a buck/boost regulator which I think may be a little too complicated for a beginner project.

__________________
--- The days of the digital watch are numbered. ---

 

I can go to 4.5 V. I was just using 3 to keep the total enclosure as small as I can.

 

Is this mains powered or battery?

__________________

 

It is Battery-powered

 

Then use a 9V. Its about the same size as 2 AA batteries.

 

I can certainly do that as well....my main problem is finding the correct pot switch that will do the job and is small enough.